Previously proposed continuous cast systems used in resin systems that polymerize have a section of the former that introduces heat to the product, and a section of the former that carries out the post cure process. This generally makes for a long system that requires a large amount of critical control area. In U.S. Pat. No. 3,376,371 (issued Apr. 2, 1968-Opel et al) the apparatus is 50.3 meters long and in U.S. Pat. No. 4,046,850 (issued Sep. 6, 1977-Kato et al) the apparatus is 15 meters in length. Other systems that are shorter operate at such a slow speed that their commercial use in the production of this type of product is questionable. An example is U.S. Pat. No. 3,422,178 (issued Jan. 14, 1969-Junker et al) which has a length of 3.65 meters and referring to the examples cited in this patent it appears to produce the product at a rate of from 0.114 to 0.216 meters per minute. The longer system described in U.S. Pat. No. 4,046,850 gives examples of speeds of 0.217 to 0.624 meters per minute. The longest system described in U.S. Pat. No. 3,376,371 gives a belt speed of 0.914 meters per minute.
In the above-mentioned prior systems it will be seen that an appropriate length of time is required for the adequate transfer of heat from the heat source to the product being formed or produced to effect polymerization as desired. The methods used to achieve this have been either running a short system slowly or providing a longer more complicated system running at a faster speed. This increases the critical dimensions of the forming area of the system. Furthermore, the product being formed has to reach sufficient strength before it can tolerate the removal from the surfaces which define the product shape, due to the nature of the belts required for these systems and their poor natural release properties. This also dictates the speed and/or length of the belt forming section.
The use of the cavity formed between the metal belts, by whatever means, as a heat exchanger is believed to be an inefficient method when time is a factor. This inefficiency becomes magnified the thicker the cross-section of the part that is being formed. The cavity formed by the belts to define the product being formed is best suited for that purpose alone and deformity thereof should be avoided so far as possible. Efficient transfer of heat requires much greater areas of exposure of product to the heated surface.